JLAB

Iapetus

"eye"-AA-pih-tuss is Saturn's third-largest moon after Titan and Rhea and, like Rhea, was discovered by Giovanni Cassini in 1671. It was named based upon a suggestion from John Herschel (son of the discoverer of Uranus, William Herschel) for the Titans of Greek mythology, the brothers and sisters of Cronos (Saturn). Iapetus has a distinctive two-tone coloration; part of it is red-brown, while part is bright gray. Features on Iapetus are named for people and places from the French Song of Roland, including Charlemagne Crater and the bright northern region Roncevaux Terra. In 2004 the Cassini orbiter found an equatorial ridge running over 800 miles long and 10 miles wide that gives Iapetus some of the highest peaks in the solar system; its existence has not yet been explained.

Monmouth (June 28, 1778)

The last major battle of the Northern theater of the war; its outcome was inconclusive. American general Charles Lee was court-martialed for his actions at Monmouth. Molly Pitcher became famous for fighting in this battle in place of her husband.

Germantown (October 4, 1777)

Washington's attack on Germantown was the Continental Army's last major effort to retake Philadelphia before the winter of 1777-1778. After this defeat, Washington's troops wintered at Valley Forge.

Sergei Korolev

, known until his death by the pseudonym "Chief Designer", headed design and construction for the Soviet long-range ballistic missile program, as well as the R-7 ICBM program. This work urged similar innovations in the U.S. Earlier in his career, Korolev designed a rocket-powered glider, though he was imprisoned and forced into slave labor during the Great Purge. In the 1950s, he personally oversaw Sputnik and Sputnik 2, and he returned to the R-7, modifying it for lunar insertion of robotic probes. His final years were spent devising soft-landing methods for manned lunar missions.

Grand Theft Auto

An immensely successful Rockstar Games series that has repeatedly drawn criticism for its level of violence. Grand Theft Auto games are played in open world "sandboxes" that give the player the ability to do virtually anything they want. The series is set in satirized versions of real U.S. cities, with GTA III and GTA IV taking place in the New York knock-off Liberty City, GTA: Vice City taking place in a fictionalized Miami, and GTA: San Andreas and GTA V taking place in Los Santos, a send-up of Los Angeles.

Final Fantasy

A long-running Japanese role-playing game (JRPG) series, whose 15th main installment was released in November 2016. Final Fantasy VII, released in 1997, was a massive success and (at the time) a technical marvel that helped popularize the Sony PlayStation. Some notable protagonists from the series include Cecil Harvey (IV), Cloud Strife (VII), and Tidus (X). The series is closely associated with composer Nobuo Uematsu, who created the soundtracks for the first nine games as well as part of the tenth.

Ticonderoga (May 10, 1775)

A small but symbolic victory for the American forces led by Ethan Allen and Benedict Arnold. The Green Mountain Boys captured Fort Ticonderoga on Lake Champlain from the British and transported its cannons to Boston.

Cowpens (January 17, 1781)

A turning point in the American recapture of South Carolina. Daniel Morgan commanded the Continentals and Banastre Tarleton led the British. The Battle was fought between the Pacolet and Broad Rivers.

StarCraft

Another Blizzard RTS series, with a science fiction theme. The game features three playable races: Terrans (humans), Zerg (a single-minded collective of insect-like aliens), and Protoss (strong, humanoid aliens with psionic powers). StarCraft II, the series's latest entry, was split into three parts whose stories each focused on one of the three races. Major characters in the series include Jim Raynor, a Terran leader, and Sarah Kerrigan, a former Terran psychic corrupted by the Zerg.

Sonic the Hedgehog

Flagship Sega franchise, starring a namesake blue hedgehog that runs at high speeds. Sonic first appeared on the Sega Genesis console in 1991, and is accompanied in later games by allies such as Tails (an orange, two-tailed fox) and Knuckles (a red echidna). The series's villain is Dr. Eggman, known as Dr. Robotnik in the early Genesis games. Though the series has maintained popularity for over two decades, more recent games have had considerably less success than the first three Genesis games.

Phobos

Both Phobos ("fear") and Mars' smaller moon Deimos ("dread") were discovered by Asaph Hall III in 1877. At just 3,700 miles above the Martian surface, Phobos orbits more closely to its planet than any other moon in the Solar System. Because it orbits Mars faster than Mars rotates, each day it appears (from the Martian surface) to set twice in the east. Geological features on Phobos, including the Stickney Crater, are primarily named for either astronomers (Stickney was the maiden name of Asaph Hall's wife) or characters from Jonathan Swift's Gulliver's Travels. In 1971 the U.S.'s Mariner IX became the first spacecraft to provide close-up photos of Phobos.

Battle of Okinawa (April to June 1945)

Codenamed Operation Iceberg, the invasion of Okinawa was the last major ground battle in the Pacific theater of World War II. Kakazu Ridge and Shuri Castle were among the positions Japanese troops defended against U.S. Marine and Army units. Okinawa was the high point of Japanese kamikaze attacks; over 1,500 suicide missions were sent against the Allied invasion fleet. The heavy casualties sustained by both sides on Okinawa and the suicidal bravery of the Japanese military encouraged American planners to use atomic weapons on Hiroshima and Nagasaki instead of launching Operation Downfall, the projected late-1945 conventional invasion of the Japanese home islands.

Call of Duty

First-person shooter (FPS) series published by Activision. The first three games centered on World War II, while more recent editions—starting with 2007's Modern Warfare—have largely taken place in contemporary and near-future settings, and have courted controversy for such things as a level in which the player kills civilians while participating in a terrorist attack. The series is celebrated for its multiplayer modes, including cooperative Zombie modes.

Battle of Bataan (January to May 1942)

Immediately after the attack on Pearl Harbor, Japanese bombers struck the Philippine island Luzon, forcing the Americans to retreat to the Bataan Peninsula, where they held out for four months. General Douglas MacArthur vowed "I shall return" before evacuating to Australia and leaving command to Jonathan Wainwright, who retreated to the island of Corregidor and surrendered on May 6. The prisoners from Bataan were sent on a "death march" 80 miles to San Fernando with minimal food, water, and medical supplies; those that fell behind were beaten. Japanese General Masaharu Homma was executed in 1946 for his role in the war crime.

Mohs scale

Invented by Friedrich Mohs in 1812, the Mohs scale is based on the abilities of minerals to scratch one another. The original scale assigned a value of 1 to talc, which can be scratched by essentially every solid known, and a value of 10 to diamond, which (among naturally occurring minerals) can only be scratched by other diamonds. The steps are of arbitrary size, with a 1-point difference corresponding to anywhere from a 1.5-fold to a 4-fold increase in hardness; diamond is about 1600 times harder than talc. Following the discovery of more ultra-hard minerals, scientists have proposed extending the scale so that diamond is 15 instead of 10.)

Battle of Iwo Jima (February to March 1945)

Iwo Jima is an isolated volcanic island between the Marianas and Honshu; early in 1945 it was strategically important as a base for American air attacks on the Japanese home islands. The defenders were led by General Tadamichi Kuribayashi, who attempted to prolong the battle indefinitely by digging an elaborate system of tunnels to protect his troops. The U.S Marines who stormed the island starting in February 1945 sustained thousands of casualties. Joe Rosenthal's photograph of Marines raising the flag on Iwo's Mount Suribachi is one of the best known images of the Second World War.

Sino-Japanese War (1937-1945)

Japan's invasion of China was the primary cause of World War II in East Asia. As early as 1931, Japanese forces occupied Manchuria and set up a puppet state called Manchukuo. The Marco Polo Bridge Incident of 1937 resulted in open war between Japan and China. Japanese forces committed notorious atrocities during the invasion of China, including the 1937 massacres known as the Rape of Nanking. The Chinese war effort was hindered by internal conflict between Chiang Kai-Shek's Nationalist Kuomintang government and the communist insurgency led by Mao Zedong. Between 1942 and 1945 central China was largely cut off from the outside world due to Japanese conquest of coastal ports; Allied support was limited to air power deployed over the Himalayas from India, including the fighter pilots known as the "Flying Tigers."

Fall of Singapore (February 1942)

Japan's offensive in southeast Asia also struck at the British Empire. Japanese aircraft sank the British battleship Prince of Wales and drove obsolete British aircraft from the skies over the Malay Peninsula. Allied troops were driven back toward Singapore, Britain's major base in the Far East. Reinforcements from Britain and Australia arrived too late to repair the situation, and British general Arthur Percival was forced to surrender in February 1942. The loss of Singapore stunned the British Empire. Many Indian prisoners captured at Singapore switched sides to fight for the Japanese; British and Australian POWs labored in terrible conditions on the Siam-Burma railway depicted in the novel The Bridge over the River Kwai.

Mach number

Mach numbers measure speed. Based on a suggestion by Swiss aeronautical engineer Jakob Ackeret, it was named after Ernst Mach, an Austrian physicist who studied — among other things — the Doppler effect, sensory perception, and the origin of inertia. The Mach number is defined as the ratio of the speed of an object to the speed of sound in the same medium. So an object moving at the speed of sound (which in dry air at 20°C is about 343 m/s) has a speed of Mach 1, and an object moving at twice the speed of sound has a speed of Mach 2.

Battle of Midway (June 1942)

Midway is considered the turning point of World War II in the Pacific. Japanese Admiral Yamamoto launched attacks on both Midway Island — an atoll northwest of Hawaii — and the Aleutian Islands in Alaska, but the Americans had broken the Japanese naval code and were forewarned. Admiral Chester W. Nimitz's American fleet lost the aircraft carrier Yorktown, but American dive-bombers destroyed four Japanese carriers: Soryu, Akagi, Kaga, and Hiryu. The loss of four irreplaceable aircraft carriers and the death of the best-trained Japanese pilots crippled Japanese naval aviation for the duration of the war.

Trenton (December 26, 1776)

Occurred early in the morning after George Washington's crossing of the Delaware River on Christmas night. The Hessians, under the command of Johann Rall, were surprised and about two thirds of them were captured.

the Battle of Kadesh (1274 BC

One of the earliest battles in recorded history was fought near the Orontes River in what is now Syria between Egyptian Pharaoh Ramses II and the Hittite king Muwatalli II. Although Ramses proclaimed a great victory for himself, he was lucky to achieve a stalemate after being ambushed by Hittite chariots. Kadesh was probably the largest chariot battle in history, with over 5,000 chariots engaged. The Egyptian chariots were smaller and faster than those used by the Hittites, which gave the Egyptians an advantage.

Deimos

One-seventh the mass of Phobos and further away from the Martian surface, Deimos was found by Asaph Hall at the U.S. Naval Observatory six days before he discovered Phobos. Its largest and only named craters are Swift and Voltaire; Deimos's surface doesn't appear as rough as Phobos's because regolith has filled in some of the craters. A still-controversial and unproven hypothesis holds that Deimos (and possibly Phobos as well) were asteroids perturbed out of their orbit by Jupiter and then captured by the gravity of Mars.

Marathon (490 BC

Persian King Darius I's invasion of mainland Greece ended with a decisive victory for Miltiades and the Athenians. The defeated Persian commanders were Datis and Artaphernes. Among the few Athenian dead of the battle were archon Callimachus and the general Stesilaos. Legend has it that the Greek messenger Pheidippides ran to Athens with news of the victory, but collapsed upon arrival. This is the inspiration for the modern race known as the "marathon."

Pokémon

RPG series about animal-like "pocket monsters," and the basis for the long-running Japanese animated series about trainer Ash Ketchum. Pokémon games are typically released in pairs that differ in which Pokémon are available, such as Red/Blue, Gold/Silver, X/Y, and 2016's Sun/Moon. Notable Pokémon include Pikachu, Charizard, Lucario, Greninja, and Mewtwo. A mobile version, Pokémon Go, was released in 2016 to massive success.

Super Mario

The character Mario first appeared in the arcade game Donkey Kong, in which he was originally named "Jumpman." Created by Nintendo's Shigeru Miyamoto, Mario has since appeared in over 200 games, including the iconic Super Mario Bros., which launched with the Nintendo Entertainment System in 1985. Mario, along with his brother Luigi, his nemesis Bowser, and his allies Yoshi, Princess Peach, and Toad, have also appeared in numerous spinoff series like Mario Kart, Mario Tennis, Paper Mario, and Super Smash Bros.

WarCraft

Series developed by Blizzard Entertainment that helped popularize the real-time strategy (RTS) genre, in which players fight against each other by constructing buildings and armies as quickly as possible. The first game in the series pitted Humans against Orcs; later games added Night Elves and Undead. The 2004 MMORPG (massively multiplayer online RPG) World of Warcraft, set in the same universe, has had over 10 million subscribers.

Camden (August 16, 1780)

The American defeat was part of the British "southern strategy," which included the earlier capture of Charleston and Savannah. Charles Cornwallis inflicted a humiliating defeat on the forces of Horatio Gates.

Battle of Leyte Gulf (October 1944)

The American landings on the island of Leyte in the fall of 1944 fulfilled Douglas MacArthur's promise to return to the Philippines. Most of the Imperial Japanese Navy's remaining strength emerged to challenge the Allied landing, setting up one of the largest naval battles in world history. American admiral William "Bull" Halsey was criticized for the poorly-coordinated response to the Japanese attack. Nevertheless, American ships, aircraft, and submarines were able to destroy more than two dozen Japanese vessels, including the giant battleship Musashi. The Japanese position was by now so desperate that Japan began the practice of suicidal kamikaze attacks on Allied naval vessels.

Quebec (December 31, 1775)

The culmination of a failed invasion of Canada by American colonists. In a blinding snowstorm, the American general Richard Montgomery was killed in battle, Benedict Arnold was wounded, and Daniel Morgan was captured.

Madden NFL

The Madden series (which, prior to 1993, was simply known as John Madden Football due to licensing issues), has featured yearly installments since 1990 and is published by EA Sports (which also publishes the FIFA soccer series). Madden NFL traditionally features a different player on its box art each year; an apparent string of injuries to and poor seasons by players on the cover of that particular year's game has become known as the Madden Curse.

Pauling scale

The Pauling scale, devised by Linus Pauling in 1932, is one of several scales that measure electronegativity, the extent to which atoms attract electrons in chemical bonds. Higher values correspond to stronger attractions. Francium has the lowest value, about 0.7, while fluorine has the highest value, about 4.0. (Noble gases are not assigned values on the Pauling scale, since they were not known to form any bonds when Pauling devised it.) Differences in electronegativity characterize bonds: the greater the difference, the more ionic the bond.

Richter scale

The Richter scale measures earthquake intensity. Developed by Caltech professor Charles Francis Richter, it measures the shaking intensity associated with earthquakes, as quantified by the amplitude of vibrations on a seismograph. A magnitude-5.0 earthquake will have an amplitude 10 times larger than that of a magnitude 4.0 quake. The energy associated with an earthquake is actually proportional to the 3/2 power of the magnitude: a 1-point difference on the Richter scale corresponds to a 103/2-fold (about 31.6) difference in energy. Because of difficulties in measuring the magnitudes of large earthquakes, the Richter scale has been superseded by the moment magnitude scale, which uses a different formula but retains the logarithmic nature (and correlates to measurements on the Richter scale).

Saffir-Simpson scale

The Saffir-Simpson scale is a measure of wind speed and damage from hurricanes. It was developed in 1971 by Herbert Saffir, a civil engineer, and Robert Simpson, then the director of the National Hurricane Center. It rates hurricanes on a 1-to-5 scale: a 1 corresponds to a wind speed of 74 to 95 miles per hour, which causes "some damage." A 5 causes "catastrophic damage," with wind speeds over 157 miles per hour and affected areas uninhabitable for weeks or months.

Yorktown (ended October 19, 1781)

The Siege of Yorktown essentially ended the American Revolutionary War, although the Treaty of Paris wasn't signed until two years later. George Washington, with help from the French navy under the Comte de Grasse, surrounded the forces of Cornwallis and forced the British to surrender. General Charles O'Hara presented Cornwallis's sword of surrender.

Lexington and Concord (April 19, 1775)

The first battles of the American Revolutionary War were skirmishes near Boston in the two towns of Lexington and Concord, as well as Cambridge, Lincoln and Menotomy. British regulars under Francis Smith attempted to destroy the supplies of the colonial militia, but were stopped by Minutemen. Ralph Waldo Emerson described the first shot as the "shot heard round the world."

Beaufort wind force scale

The first official use of the Beaufort scale was on the voyage of the HMS Beagle in 1831, which was led by Robert FitzRoy, who had been trained by the scale's namesake, Sir Francis Beaufort, a rear admiral in the British Navy. The Beaufort scale is primarily based on wind speed, but also incorporates descriptions of wave height, sea conditions, and land conditions. It starts at 0, corresponding to "calm" winds with a speed less than 1 knot. In most parts of the world, it stops at 12, which is designated "hurricane-force winds." Scores of 2 to 6 are called "breezes," and scores of 7 to 10 are called "gales." Since 1946 the median wind speed for each step has been defined as 1.87 B3/2, where B is the number on the Beaufort scale.

Long Island (August 27, 1776)

The largest battle of the entire war, Long Island (or Brooklyn Heights) resulted in the British capture of New York. William Howe defeated George Washington.

Triton

The largest moon of Neptune and the only large moon with a retrograde orbit (that is, an orbit opposite to the rotation of its planet), Triton is the seventh-largest moon in the solar system and is thought to have been captured from the Kuiper Belt. For over 100 years after its 1846 discovery, Triton was thought to be Neptune's only moon; Nereid wasn't discovered until 1949. (There are thirteen known satellites now.) Triton is geologically active and has geysers that are assumed to erupt nitrogen. Because of the activity, impact craters on Triton are relatively scarce; most of the larger craters were formed by volcanic activity. Triton orbits around Neptune in almost a perfect circle. Voyager 2 visited Triton in 1989 and is the only space probe to have done so (and no more are currently planned). Much of Triton's western hemisphere consists of an unexplained series of fissures and depressions sometimes called "cantaloupe terrain." Triton's features are named after various water spirits, monsters, and sacred waters from mythology.

Saratoga (ended October 17, 1777)

The major turning point of the American Revolution because the American victory led France to join the war. British General John Burgoyne led an invasion into New York from Canada with hopes of meeting another British army and splitting the American colonies. The final surrender was preceded by battles at Freeman's Farm and Bemis Heights. Horatio Gates led the American forces.

Earth's moon

The moon, also called Luna, is the fifth-largest satellite in the solar system, the largest relative to the size of the planet it orbits, and the second densest. The USSR's Luna unmanned spacecraft first reached the moon in 1959, and Apollo 8 became the first manned mission to orbit the moon, in 1968. The 1967 Outer Space Treaty guarantees the rights of all nations to explore the moon for peaceful purposes. The flat dark lunar plains are called maria (singular: mare) and are mainly concentrated on the near side of the moon. The most famous one is Mare Tranquillitatis, the Sea of Tranquility, where Apollo 11 first landed on the moon in 1969. The Apollo program landed on the moon five more times.

pH scale

The pH scale, developed by S. P. L. Sørensen in 1909, is used to quantify acidity. The pH (power of hydrogen) of a solution is defined as the opposite of the (base-10) logarithm of the concentration of protons in a solution: pH = -log10[H+]. (The brackets are standard notation in chemistry for "the concentration of.") Thus, greater concentrations of protons correspond to smaller pH values. At 25°C, the neutral (neither acidic nor basic) pH is 7; solutions with a pH less than 7 are considered acidic, and solutions with a pH greater than 7 are considered basic.

Temperature scales

The scales most frequently used to measure temperatures in science are the Kelvin and Celsius scales. The Celsius scale, developed by Swedish scientist Anders Celsius in the early 1700s, assigns a value of 0°C to the freezing point of water (at a pressure of 1 atmosphere), and 100°C to the boiling point of water (at the same pressure). The Kelvin scale is based on the triple point of water, the point at which water's solid, liquid, and gaseous phases can coexist in equilibrium: 1 K is defined as 1/273.16 of the temperature of water at its triple point. Kelvins are treated like all other SI units: a temperature of 100 K is read as "one hundred kelvins," not "one hundred degrees kelvin." Differences on the Celsius scale have the same magnitude as differences on the Kelvin scale: a gap of 1°C between temperatures is the same as a gap of 1 K. Therefore the lowest possible temperature, absolute zero (0 K) is equal to -273.15°C, and (at a pressure of 1 atmosphere) water freezes at 273.15 K and boils at 373.15 K.

Fujita-Pearson and Enhanced Fujita scales

These scales measure tornado strength. The Fujita-Pearson scale was introduced in 1971 by Ted Fujita, a meteorology professor at the University of Chicago, and Allen Pearson, director of what is now the Storm Prediction Center. The original scale went from F0 (wind speeds lower than hurricane force, which should cause little to no damage) to F5 (wind speeds of 260 miles per hour, which should cause "incredible damage"). Fujita also included an "inconceivable damage" category for tornados exceeding 319 miles per hour (theoretically possible, but no such tornado has ever been observed). In 2007 the Enhanced Fujita (EF) scale was introduced, narrowing the speed ranges for each category: an EF5 begins at "just" 200 miles per hour.

Bunker Hill (June 17, 1775)

This British pyrrhic victory outside Boston resulted in the capture of the Charlestown Peninsula, but showed that colonial troops could stand up to British regulars. Most of the fighting actually occurred on Breed's Hill, not Bunker Hill.

Guadalcanal Campaign (August 1942 to February 1943)

This first Allied counteroffensive in the Pacific targeted Guadalcanal, an island in the Solomons, to secure communications between the U.S. Pacific coast and Australia. "Operation Watchtower" was the codename for the initial U.S. Marine landings, which secured an airbase at Henderson Field and held off a Japanese counterattack on Edson's Ridge. The naval battle of Savo Island took place between American ships and Japanese forces (the so-called "Tokyo Express") trying to resupply troops on Guadalcanal. By early 1943, Allied dominance of the seas and skies around Guadalcanal forced Japan to withdraw its remaining troops.

Titania and Oberon

Uranus's largest moons, Titania and Oberon, are named for characters from Shakespeare's A Midsummer Night's Dream. (Other Uranian moons are named for characters from either Shakespeare or Alexander Pope.) They were discovered on the same day in 1787 by William Herschel, who also discovered Uranus itself in 1781. In 1986 Voyager 2 became the only spacecraft to date to visit the Uranian moons. Because Uranus orbits the sun almost on its side and Titania and Oberon orbit Uranus in the same plane as its equator, the moons have extreme seasons: Titania's poles spend over 42 years in nonstop sunlight followed by 42 years of darkness. Most of Titania's features are named for settings or female characters from Shakespeare — its largest crater is Gertrude Crater, after Hamlet's mother — while most of Oberon's are named after settings or male characters from Shakespeare. However, Oberon's largest feature is Mommur Chasma, which is named from a French epic poem.

SM3A

replaced failed gyroscope systems.

Gene Kranz

was a trained aeronautical engineer and pilot, he is best known for his Flight Directorship during the Mercury and Apollo projects. He presided over a departure from NASA's traditional incremental testing structure, in favor of a more aggressive, manned campaign ("all-up testing"). As part of the Apollo 13 "white team," Kranz and his associates engineered the free-return trajectory and human-factors management that brought the Apollo 13 crew back safely after a near-fatal spacecraft anomaly.

Voskhod 1 and Voskhod 2

were the only two missions of the Voskhod program, and were superseded quickly by the Soyuz program. The spacecrafts made use of Sergei Korolev's designs. Korolev himself was preoccupied with the Moon race, again in a position of favor after the fall of Khrushchev (though Korolev died before the designs were used). Voskhod 1 was the first flight to contain multiple astronauts, and Voskhod 2 was the platform for the first EVA (extra-vehicular activity or "spacewalk"). Alexey Leonov, who conducted the spacewalk on Voskhod 2, also participated in the later Apollo-Soyuz Test Project.

The Legend of Zelda

Also created by Shigeru Miyamoto. Games in the Zelda series star the green-clad Link, who typically must rescue Princess Zelda from the evil Ganon (who sometimes appears in his humanoid form, Ganondorf). Recurring weapons in the series include the Master Sword, boomerang, bombs, and hookshot. Much of the series's lore centers on the Triforce, a set of three golden triangles whose constituent parts represent power, wisdom, and courage.

Attack on Pearl Harbor (December 1941)

Japanese plans for domination of the Pacific called for a surprise attack on the U.S. Navy base at Pearl Harbor in Hawaii; wrecking the American Pacific Fleet would allow the Japanese navy to invade southeast Asia with minimal opposition. Admiral Isoroku Yamamoto planned the Japanese strike, which sent carrier-based dive bombers and torpedo bombers to Oahu on Sunday, December 7, 1941. Four American battleships, including the USS Arizona, were sunk; the American aircraft carriers were at sea away from Pearl Harbor at the time of the attack. The losses sustained at Pearl Harbor shocked the previously neutral United States into entering World War II. President Franklin Roosevelt's address to Congress described December 7 as a "date which will live in infamy."

Battle of the Coral Sea (May 1942)

The Battle of the Coral Sea resulted from Japanese ambitions to invade Port Moresby, an Allied base in New Guinea. Frank Jack Fletcher's American fleet damaged two Japanese aircraft carriers, Shokaku and Zuikaku. The U.S. Navy's major loss was the carrier Lexington. The battle, a tactical draw, prevented the Japanese from attacking Port Moresby. It is notable for being the first naval battle fought entirely by aircraft — neither fleet was ever in visual range of the other's ships.

Decibel scale

The decibel scale can describe any kind of power, but is most commonly used to describe the intensity of sound waves. The decibel (abbreviated dB) is one tenth of a larger unit, the bel (abbreviated B), named after inventor Alexander Graham Bell. The intensity of a sound in decibels is given by the formula I = 10 log(P1/P0), where P1 is the intensity of the sound being measured (in watts per square meter) and P0 is a reference intensity, which is based on the least powerful sound wave that can be detected by the average human ear (namely 10-12 W/m2). A 10-dB increase in sound intensity corresponds to multiplying the energy of the sound wave by 10. A normal conversation has a volume of about 70 dB.

Charon

The largest satellite of the dwarf planet Pluto, Charon wasn't discovered until 1978. (As of 2013, Pluto has five known moons, the last two discovered in 2011 and 2012.) Unlike Pluto, which is covered with nitrogen and methane ices, Charon appears to be covered in water ice and may also have active cryo-geysers. Because the center of mass of the Pluto-Charon system lies outside of either one, Charon doesn't truly orbit Pluto; when Pluto was reclassified as a dwarf planet in 2006, an argument was made (but not accepted) to classify Pluto-Charon as a binary system. The IAU still considers Charon, which is roughly half the size but has only 11% the mass of Pluto, to be a satellite. The New Horizons mission visited Charon and Pluto in 2015. Charon was named by its discoverer, James Christy of the Flagstaff Naval Observatory; the IAU approved the name in 1985. Internationally Charon is pronounced like the Greek mythological figure, "CARE-on", but Christy's choice of name was inspired by his wife Charlene, so NASA and New Horizons personnel use "SHARE-on".

Hubble Space Telescope Servicing Missions (SM1, SM2, SM3A, SM3B, and SM4)

all utilized spacewalks staged from a Space Shuttle.

STS-51-L and STS-107 (the Challenger and Columbia accidents respectively)

are two Space Shuttle (or Space Transportation System) launches known mostly for their accidents and subsequent losses of life. The Challenger disaster was attributed by the Rogers Commission (the investigative body set up after the accident) to poor performance of the solid rocket booster (SRB) O-rings. The O-rings lost integrity and became brittle at low temperatures, such as those present on the morning of the launch. The failure of the O-rings caused "blow-by," where hot gasses escaped the booster joint, ultimately resulting in the destruction of Challenger. The Rogers Commission also cited both NASA and SRB contractor Morton Thiokol for a failure to redesign the SRB joint, known to be dangerous—manifestations of "go fever." According to the Columbia Accident Investigation Board, the disaster on STS-107 was due to a piece of foam from the external fuel tank hitting and breaching the left wing of the Orbiter during launch. The breach damaged the heat shielding, allowing hot gas to enter the Orbiter during re-entry. Ultimately, that damage caused the vehicle to disintegrate over Texas. Both missions resulted in the complete loss of crew (seven crew were on each mission) and orbiters. Both modes of failure had been previously observed in earlier missions, but went un-fixed because those missions were successful.

The Hershey-Chase experiment (1952)

by Alfred Hershey and Martha Chase, demonstrated that the material responsible for inheritance of traits was DNA rather than protein. The experiment was carried out by creating radiolabeled T2 bacteriophages (viruses that infect bacteria). In one population, the phages' DNA contained phosphorus-32 in its backbone; in the other population, the phages' proteins contained sulfur-35. The phages were then allowed to infect E. coli. After using a centrifuge to remove the viral coats from the bacteria, Hershey and Chase found that the viruses labeled with sulfur did not transfer their radioactivity to the cells, while the viruses labeled with phosphorus did. This result, combined with other experiments, demonstrated that the genetic material was DNA, not protein.

The launch of Sputnik 1, the first artificial satellite,

by the USSR kicked off the so-called "Space Race." The Space Race was manifestation of the Cold War where successes in launching objects and people into space was seen as a proxy for capacity to build intercontinental ballistic missiles. Sputnik 1 was originally intended to carry many scientific instruments, but those instruments were descoped, in favor of a simple radio transmitter. That transmitter broadcasted a "beep" at a specified interval, allowing scientists to map its deceleration as a result of atmospheric drag. Sputnik 1 was followed by Sputnik 2, which carried a dog named Laika (meaning "barker") into low-earth orbit, and was destroyed upon re-entry.

The Michelson-Morley experiment (1887)

conducted by Albert Michelson and Edward Morley at what is now Case Western Reserve University, disproved the existence of the luminiferous aether, a hypothetical medium through which light waves supposedly moved. (The aether is sometimes called simply "ether," but is not to be confused with ethers from organic chemistry.) The experiment used an interferometer, a device that splits a beam of light and aims it using mirrors to allow the beam to interfere with itself; the interferometer was mounted on a slab of marble floating in a pool of mercury so that it could turn without friction, to eliminate the possibility that the interferometer was misoriented. While Michelson and Morley expected to find a shift in the interference pattern's fringes as a result of the ether, the experiment showed that the Earth had no motion relative to the ether, suggesting that the ether did not exist. Often called the most famous failed experiment in science, the Michelson-Morley experiment is a fundamental test of special relativity.

The Stern-Gerlach experiment (1922)

conducted by Otto Stern and Walther Gerlach, demonstrated that the angular momentum of an atom is quantized. A beam of silver atoms was fired through an inhomogeneous magnetic field (one that varies through space). Instead of hitting a screen in a continuous distribution, they hit at discrete points, demonstrating the quantized nature of angular momentum. This experiment was actually performed several years before the concept of electron spin was even proposed. A variant on this experiment was used to create an energy source for the first hydrogen maser.

SM1

corrected Hubble's flawed optics by installing COSTAR (a corrective optics system), while removing the High-Speed Photometer to make room. It also replaced the original Wide Field and Planetary Camera, or WFPC "wiff-pick", with WFPC2, which a camera that had optical correction built in.

Hellmuth Walter

designed the Starthilfe (takeoff assist) rocket propulsion units for the Messerschmidt Me 163 and the vertical-takeoff Bachem Ba 349 aircrafts, used by the German Luftwaffe in World War II. He also was awarded a patent in 1925 for suggesting that a catalyzed decomposition of hydrogen peroxide could provide oxygen for combustion.

The short and turbulent period of the Three Kingdoms (AD 184-280

has had an enormous cultural impact thanks to the classic Chinese novel Romance of the Three Kingdoms. After a period of disunion, the lands of the former Han dynasty coalesced into three kingdoms: Cao Wei north of the Yangtze, Eastern Wu in the lower Yangtze, and Shu Han in the Sichuan region. The Battle of Red Cliffs (AD 208) was fought during this period. Under the leadership of the Sima family, Cao Wei managed to defeat the other two kingdoms. The reunification was, however, short-lived. For the next four centuries, China went through a period known as the Southern and Northern Dynasties.

Hermann Oberth

imagined at the age of 14 a recoil rocket, which could propel itself by exhausting gas from its base. He also lends his name to the Oberth effect, a phenomenon by which rockets operate more efficiently when moving at higher speeds, and formulated the idea behind multiple-stage rocketry. Oberth also mentored many German rocket engineers through the Verein für Raumschiffahrt (Spaceflight Society), whose formation was inspired partially by Oberth's writing.

Konstantin Tsiolkovsky's

interest in science manifested first through his science fiction writings, but he gained more notoriety for his eponymous rocket equation. The Tsiolkovsky equation, as published in 1903's Exploration of Outer Space by Means of Rocket Device, relates a rocket's speed with its mass, the speed of its exhaust, and the exhaust's mass (an application of Newton's laws of motion.) The equation is also connected with the idea of specific impulse, a measure of a rocket's efficiency. Tsiolkovsky also published theoretical studies on the capabilities of multi-stage, liquid-fueled engines, gyroscopes, and escape velocities.

The Apollo-Soyuz Test Project

marked a definite end to the Space Race, and was a symbol of the de-escalation of tensions between the US and the USSR. Deke Slayton, an original Mercury 7 astronaut grounded for medical reasons until 1973, was accompanied by Tom Stafford and Vance Brand on the last launch of Apollo before the advent of the Space Shuttle. The mission demonstrated that two dissimilar spacecraft could rendezvous and dock while in space (an Apollo Command Module and Soyuz 19 docked), and also enabled the crew of Soyuz to photograph the Sun's corona through an artificial eclipse created by the Apollo spacecraft. Each spacecraft also carried out independent experiments.

The Han dynasty (206 BC - AD 220

is considered a golden age of Chinese civilization; its influence was so great that the majority ethnic group in China is still called the Han. Its founder, Liu Bang (later Emperor Gaozu), was born a peasant. Through resourceful recruitment of talented followers and strategic violation of ceasefire agreement with his rival Xiang Yu, Liu Bang managed to reunite China and established his capital at Chang'an (modern Xi'an). Instability in the early years of the Han dynasty was caused by the depredations of the nomadic Xiongnu, a problem that was solved by its seventh emperor, Wudi. Emperor Wu, considered one of the greatest rulers of China, began a war of conquest against the Xiongnu and greatly expanded China's frontiers. He also formalized China's bureaucracy, sent envoys like Zhang Qian to Central Asia, and established Confucianism as the official state doctrine. Despite his success, his campaigns drained the treasury and his successors were unable to maintain the land he conquered. After a series of poor rulers, the Wang family — who claimed legitimacy through wives of various emperors — and their leader Wang Mang toppled the Han dynasty. Wang Mang established the Xin (meaning "new") dynasty and attempted to restore the ways of the Zhou dynasty, but he was unable to maintain power because of a catastrophic changing of the course of the Yellow River, which spawned peasant protest movements like the Red Eyebrows. Eventually, a scion of the Liu family — Liu Xiu — restored the Han dynasty, moving the capital to Luoyang and establishing the Eastern Han. Subsequent rebellions called the Yellow Turbans and the Five Pecks of Rice hastened the end of the Han dynasty.

The Tang dynasty (618-907

is considered another golden age of Chinese culture: during the Tang period, important poets such as Li Bai (or Li Po) and Du Fu lived, and the printing press was invented. The Tang dynasty reunited China after the collapse of the short-lived Sui dynasty, was ruled by the Li family, and had its capital at Chang'an (modern day Xi'an). Its first ruler, like the founder of the Han Dynasty, used the title of Emperor Gaozu. Gaozu was forced by his second son, Li Shimin (later Emperor Taizong), to abdicate after Li Shimin killed two of his brothers in an ambush. Despite his bloody path to power, Taizong is considered to be one of the greatest rulers in Chinese history, subjugating much of what is now western China and parts of central Asia. After his death, power came to be concentrated in the hands of Empress Wu. Empress Wu (or Wu Zetian) was the only woman to become emperor of China, and called her rule the "Second Zhou dynasty." Wu was a notable supporter of Buddhism and promoted the imperial examination, but succession troubles resulted in the premature end of her dynasty. During the reign of Emperor Xuanzong, the An Lushan rebellion (also called the An Shi rebellion) wrecked the foundations of the Tang dynasty. Although it was suppressed, the An Lushan rebellion concentrated power in the hands of regional military overlords. The dynasty had a tumultuous end in 907 that marked the beginning of the Five Dynasties and Ten Kingdoms period.

The Song dynasty (960-1279

is known for its devotion to cultural activities instead of warfare and for the establishment of Neo-Confucianism as state doctrine, with the imperial examination as the primary way of recruiting talent. It was also during the Song dynasty that gunpowder and the compass were discovered. The Song dynasty, even in its early years, could not rule all of China proper and was forced to relinquish parts of northern China to the "barbarian" Liao dynasty, paying tribute for peace. Although like most dynasties, it began as the ventures of a military leader, its first ruler, Taizu, realized that his rival generals could take power from him. He then induced all his major commanders to retire, setting up the dominance of the scholarly elite over the military elite throughout the Song dynasty. This policy was continued by his successors. In the north, however, the Liao dynasty was eventually replaced by the militaristic Jin dynasty, who captured the Song capital, Kaifeng along with two Emperors. The remnants of the court fled across the Yangtze and established the Southern Song with a new capital at Hangzhou, maintaining peace with the Jin through annual tribute. This state of affairs was brought to an end after the Song dynasty aided the Mongols in crushing the Jin, only to discover that they themselves were the next target. Despite the might of the Mongol war machine, the Song dynasty managed to repel major Mongol offensives for nearly 40 years, before it was finally defeated.

The Shang dynasty (c. 1600-1046 BC

is the first Chinese dynasty attested from written records. Archaeological excavations at the ruins of Yin, near the modern city of Anyang, uncovered the remains of a Chinese civilization from the Bronze Age. Shang dynasty writings are found on "oracle bones," pieces of ox bone or turtle shell that were heated to produce a pattern of cracks that supposedly foretold the future.

Io

is the innermost of the four Galilean moons of Jupiter (the moons discovered by Galileo), the fourth-largest moon in the solar system, the densest moon, and the most geologically active body in the solar system, with more than 400 volcanoes. Io's features are named for characters from the Io story in Greek mythology; fire, volcano, and thunder deities from other mythologies; and characters from Dante's Inferno. Io plays a significant role in shaping Jupiter's magnetosphere. Pioneer 10 first passed by Io in December 1973.

Ganymede

is the largest moon in the solar system and the only one known to have its own magnetosphere. The third of the Galilean satellites, Ganymede was also first photographed close-up by Pioneer 10 in 1973. Galileo made six flybys of Ganymede between 1996 and 2000. Based on a suggestion from Simon Marius, Ganymede (along with many of the Jovian satellites) is named for one of Jupiter's lovers in Roman mythology; Ganymede is the only such moon named for a male figure. Many of Ganymede's features, including the Enki Catena, are given names from Egyptian and Babylonian mythology, although its largest dark plain is Galileo Regio. Ganymede is scheduled to be orbited by the European Space Agency's Jupiter Icy Moon Explorer (JUICE), currently slated for a 2022 launch.

Titan

is the largest moon of Saturn and the second largest in the solar system. Until Voyager 1 visited in 1980, it was thought to be larger than Ganymede. It is the only known satellite with a dense atmosphere — so dense that it makes observation of surface features nearly impossible except from close up — and also the only known satellite for which there is evidence of stable bodies of surface liquid. Discovered in 1655 by Christiaan Huygens, it was visited by the Cassini-Huygens mission in 2004. Titan's albedo features, such as the highly reflective area Xanadu, are named for sacred or enchanted places from world literature and mythology. Because of its nitrogen-rich atmosphere and the presence of surface liquid, Titan is often thought to be the most likely place in the solar system for microbial life to exist outside of Earth.

The Davisson-Germer experiment (1923-1927)

performed by Clinton Davisson and Lester Germer, confirmed the de Broglie hypothesis by showing that electrons can exhibit wave-like behavior. The experimenters fired electrons at a nickel crystal, and measured the diffraction patterns using an electron counter called a Faraday box (or Faraday cup) mounted on an arc so that it could detect electrons emitted at various angles. The peak intensity was observed at 50 degrees and 54 electronvolts, corresponding to the diffraction predicted for X-rays by Bragg's law. (Note that diffraction is a property of waves, not particles, and thus could only be observed if electrons can act as waves.)

The Millikan oil-drop experiment (1909)

performed by Robert A. Millikan and Harvey Fletcher to measure the charge of the electron. In the first step, the terminal velocity of an oil drop was measured, which means that the drag force (which can be calculated using Stokes' law) equals the force of gravity. From this, the mass can be calculated. Then, by turning on an electric field, the particle starts to move upward with a terminal velocity when the electric force balances out the forces of gravity and drag. Using this, and the mass of the drop, the total charge on the drop can be calculated. Millikan and Fletcher found that the total charge on the drops were always quantized—that is, always an integer multiple of some constant; specifically, the constant they found is about 1.59 × 10-19 coulombs, within 1% of the currently accepted value.

Gregor Mendel's experiments with pea plants (1860s)

pioneered the studio of genetics. Mendel, an Austrian monk, proposed the law of segregation, which holds that each organism has two alleles for each trait, which are segregated into gametes so that each gamete inherits one copy, as well as the law of independent assortment, which says that genes for individual traits are inherited independently. He supported both of those laws with experimental evidence by growing and counting pea plants. He worked with seven characteristics including plant height, seed shape, and color. His experiments primarily consisted of hybridizing plants with certain characteristics, and observing what fraction of the next generation had certain traits. His results were remarkably close to the values that would be predicted from modern genetics—close enough, in fact, that Mendel has been accused of manipulating his data.

The Meselson-Stahl experiment (1958)

proved that DNA replication is semiconservative, meaning that when a double-helix strand of DNA is duplicated, the result is two double-helix strands, each of which has one helix from the parent molecule and one newly-synthesized helix. Matthew Meselson and Franklin Stahl used E. coli grown in a medium containing only nitrogen-15; they were then allowed to synthesize DNA in an environment containing only nitrogen-14 over two generations. The net result was that in the second generation, half the DNA molecules contained nitrogen-15 in one strand and nitrogen-14 in the other, while the other half of the molecules contained only nitrogen-14.

SM3B

replaced the Faint Object Camera (FOC) with the Advanced Camera for Surveys (ACS), and also repaired NICMOS, which was installed during SM2.

SM2

replaced the Goddard High-Resolution Spectrograph (GHRS) and Faint Object Spectrograph (FOS) with improved successors.

Apollo 11

saw the first Moon landing and moonwalk by astronauts Neil Armstrong and Buzz Aldrin (astronaut Michael Collins piloted the Command Module in lunar orbit and never walked on the moon). After the Lunar Module landed in the Sea of Tranquility, Armstrong said, "Houston, Tranquility Base here. The Eagle has landed." Later stepping onto the lunar surface, he said, "That's one small step for [a] man, one giant leap for mankind." According to Chris Kraft, NASA officials chose Armstrong as the first to walk on the Moon because he was more humble than Aldrin, and because he was the Commander. However, the stated reason was that Armstrong's seat was closer to the door. Apollo 11, like other Apollo missions, launched atop a Saturn V booster.

The Rutherford gold foil experiment (1908-1913)

sometimes named after Rutherford's assistants Hans Geiger and Ernest Marsden, discovered the positively-charged nucleus of the atom; as a result, it disproved J. J. Thomson's plum pudding model. The experimenters fired alpha particles (helium nuclei) at a sheet of gold foil. (They also used other elements, including silver.) The scattered particles were detected by a screen containing zinc sulfide, which fluoresced when the alpha particles hit it. While most of the alpha particles went straight through the foil with minimal scattering, a small fraction of alpha particles were reflected back at the source. This result was unexpected, as backscattering could only occur if the alpha particles were colliding with a particle massive enough to reverse their momentum. Rutherford said "It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you."

The invading Manchus established the Qing cheeng dynasty (1644-1911

the last dynasty to rule imperial China. An important institution of the Qing dynasty was the banner system, which acted as a guaranteed welfare system for Manchus and gave them benefits in the imperial examination (positions were often duplicated, with one Han Chinese and one Manchu from the banners). The foundations of the Qing dynasty were established under its second ruler, the Kangxi Emperor, who put down the Revolt of the Three Feudatories. He is also famous for the Kangxi dictionary, which is known for popularizing the system of Chinese radicals. During the last century of Qing rule, China was weakened both by foreign attacks (the Opium Wars against Britain) and internal dissent (the devastating Taiping Rebellion of 1850-1864). Attempts to modernize Qing rule (the Self-Strengthening Movement and the Hundred Days' Reform of 1898) proved inconclusive. Qing Dowager Express Cixi, who opposed the reformers, was implicated in the Boxer Rebellion, an anti-foreign uprising of 1900 that caused eight Western nations to send military forces to Beijing. China's last emperor was Puyi, who came to the throne at the age of two in 1906. The 1911 Xinhai Revolution ended the Qing Dynasty and created the Republic of China.

Vostok 1 and Vostok 6

transported the first human and the first woman into space (respectively, Yuri Gagarin and Valentina Tereshkova). Gagarin's April 12, 1961 flight is still celebrated as Yuri's Night. During Vostok 1, Gagarin completed a single orbit around Earth before re-entering and parachuting out of his capsule. Vostok 6 was largely uneventful, though Tereshkova did note minor physical pains and also could not reach the scientific experiments aboard. Both Vostok 1 and 6 used Vostok-K boosters.

Theodore von Kármán

was a fluid dynamicist by training. As a graduate student at Göttingen, he described the so-called Kármán vortex street (a form of turbulence in flow going past a cylinder, which is responsible for driving the vibration or "singing" of power lines) and went on to provide the theoretical basis for the idea of turbulent flows. He contributed to the construction of the wind tunnel at the Guggenheim Aeronautical Laboratory, which eventually became the Jet Propulsion Laboratory. He also formed the company Aerojet to develop short-takeoff aircraft technologies. The Kármán line is the accepted boundary between the Earth's atmosphere and outer space, and the Kármán ogive is the shape of the cone of rockets curving into the main body, which minimizes drag during rocket burn.

Salamis (480 BC

was a major turning point and naval battle in the Greco-Persian Wars, as it signaled the beginning of the end of Persian attempts to conquer Greece. The battle is named after an island in the Saronic Gulf near Athens. Xerxes was so confident in victory that he watched the battle from a throne on the slopes of Mount Aegaleus. The Athenian general Themistocles devised a plan to lure the large, slow Persian ships into the narrow straits, where the Greek ships were able to outmaneuver and destroy much of the Persian fleet. The Persian admiral Ariabignes was killed in hand-to-hand combat, and the Queen of Halicarnassus, Artemisia, had to sink some of her allies' ships to escape.

The Yuan dynasty (1271-1368

was a short-lived dynasty established by the invading Mongols, who destroyed the Jin and Song states. Its most notable ruler was Kublai Khan, whose invasions of Japan were thwarted by typhoons that the Japanese called the kamikaze, or "divine wind." Yuan rulers were hostile to many Chinese institutions, and thus received minimal support from the Chinese elites. The Red Turban rebellion of the 1350s marked the beginning of the end for the Yuan.

Apollo 13

was supposed to land in the Fra Mauro region of the Moon. An improperly-refurbished No. 2 oxygen tank and subsequent improper repairs caused the tank to rupture during a routine "cryo-stir" before entering lunar orbit. The explosion also damaged the No. 1 oxygen tank and caused further leakage. To bring back the astronauts, the orbiter was put on a free-return trajectory around the Moon. NASA engineers also solved power-management, water-conservation, and trajectory planning problems with the help of Ken Mattingly, the primary Command Module pilot who had been grounded due to exposure to German measles. All three astronauts returned to Earth safely, and the landing site was re-assigned to the subsequent Apollo 14 mission.

The Miller-Urey experiment (1952)

was an attempt to demonstrate a possible mechanism—proposed by John Haldane and Alexander Oparin—for how life could form from inorganic chemicals. Stanley Miller and Harold Urey modeled Earth's prebiotic atmosphere as a mixture of water, methane (CH4), ammonia (NH3), and hydrogen. They allowed those four substances to react in an apparatus over a one-week period; the apparatus included a heater to convert the water to water vapor and an electrode to simulate lightning strikes. The resulting mixture contained more than 20 distinct amino acids that formed spontaneously; a more modern "volcanic" version of the experiment produced even more amino acids by including sulfur compounds.

Robert Goddard

was an early explorer of the theory and practice of launching rockets. His work provided the foundation for modern rocketry: in particular, gimballed engines (engines where the exhaust nozzles can change direction allowing the rocket to be steered), fuel pumps, steering with vanes, and gyroscopic stabilization. His seminal monograph on the subject was 1919's A Method of Reaching Extreme Altitudes. The next year, he put forward a concept for a rocket launch to the moon that was widely ridiculed in the press as being unrealistic. Goddard is the namesake of the NASA Goddard Spaceflight Center in Maryland.

Wernher von Braun

was at one time a student of Oberth in the Spaceflight Society. Von Braun is best-known for leading Nazi Germany's development and construction of the V-2 rocket (literally, "vengeance weapon"), which wreaked destruction on southern England during World War II. After World War II, he was recruited to the US as part of Operation Paperclip, and proposed to launch a space station carrying a nuclear arsenal (though he hedged the concept as "particularly dreadful"). He presided over Mercury-Redstone development as Director of NASA's newly-opened Marshall Spaceflight Center, which produced the rockets used in the Mercury spaceflights, and the Saturn V rocket used to launch the Apollo spacecraft.

Homer Hickam

was inspired by seeing Sputnik fly overhead to study rocketry in his early teens. From his coal-company town in West Virginia, he and his rocket club, The Big Creek Missile Agency, designed modest-sized rockets and won the propulsion category of the 1960 National Science Fair. After serving in Vietnam, Hickam worked at the US Army Missile Command in Germany and Huntsville. Later, he moved to NASA, where he specialized in astronaut training. He trained crews for the Hubble Space Telescope's deployment extra-vehicular activity (EVA) and the first two servicing missions.

Apollo 1

was intended to be a test of the Command/Service Module in low-Earth orbit (LEO). However, a fire on the launchpad during a test killed the three astronauts aboard (Virgil "Gus" Grissom, Roger Chaffee, and Ed White). The fire was exacerbated by the pure-oxygen, positive-pressure environment inside the capsule, and the fact that the capsule door opened inward. Both of these design elements were scrapped in subsequent missions, and the second was replaced with an outward-opening hatch nominally to facilitate spacewalks. Lessons learned from Apollo 1 were also taken into account during the design of the Space Shuttle.

SM4

was originally cancelled after the Columbia Disaster by then-NASA Administrator Sean O'Keefe, but was revived by Michael Griffin, who took over the post in 2005. SM4 installed WFC3 (made from some parts of the original WFPC) and the Cosmic Origins Spectrograph (COS), and conducted other repairs. No further repairs are planned, as much of HST's functionality will be replicated with the James Webb Space Telescope, scheduled for launch in 2018.

Thermopylae (480 BC

was the first battle of the second Persian invasion of Greece. Although the Persians under Xerxes I and his general Mardonius defeated the Spartans, King Leonidas and his Spartan troops put up a heroic defense of the pass at Thermopylae (the "hot gates"). The Greeks were betrayed by Ephialtes, who told the Persians about a path that led behind the Spartans. The battle was part of Themistocles' plan to halt the advance of the Persians. The other part of his plan was to block the Persian navy at Artemisium; a battle occurred there simultaneously.

SpaceX CRS-1 (also called SpX-1 or CRS-1)

was the first commercial mission to resupply the International Space Station (ISS). A structural failure in one of the nine Merlin engines that make up the Falcon 9 rocket first stage necessitated a longer burn with the remaining eight engines. That correction resulted in a proper orbital insertion for the primary payload (a Dragon resupply vehicle), but an unstable, decaying orbit for its secondary payload (an ORBCOMM satellite). This was taken as a proof of concept by SpaceX for the redundant, multiple-engine design. The craft successfully berthed with the ISS and successfully carried out its primary mission, re-supplying the space station and returning cargo to Earth.

The Ming dynasty (1368-1644

was the last native dynasty of China; its rulers came from the Zhu family. The use of the word "china" to describe fine porcelain originated from this period, as the Ming were well-known for producing high-quality porcelain. Its founding ruler, Zhu Yuanzhang (Emperor Hongwu), was a peasant leader of the Red Turbans who helped expel the Mongol Yuan rulers from China. He was succeeded by his grandson, who quickly lost power to Zhu Di (Emperor Yongle). During the reign of the Yongle emperor, the eunuch Zheng He led treasure fleets on seven voyages to display Chinese greatness. Zhu Di moved China's capital to Beijing. After his death, the Ming dynasty banned maritime commerce, which left the dynasty vulnerable to pirates. The Ming dynasty came to an end after the rebellion of Li Zicheng, which was caused by inadequate government response to inflation, famine, and floods. Simultaneously, the Manchu people — tributaries of the Ming from northeast China in what is now Manchuria — marched on the Great Wall. The Manchus suppressed Li Zicheng's revolt and took power in Beijing themselves.

The Zhou "Joe" dynasty (1046-256 BC

were chariot warriors who overthrew the Shang dynasty. Although the Zhou ruled for nearly 800 years, during much of the time period real power lay in the hands of feudal lords. The sacking of the Zhou capital by barbarians in 771 BC marks the beginning of the Eastern Zhou and the Spring and Autumn Period (771 BC - 476 BC). During the Spring and Autumn Period, the Hundred Schools of Thought (including Confucianism) flourished, and Sun Tzu wrote his Art of War. The end of the Zhou era devolved into the Warring States period (476 BC - 221 BC), during which power coalesced into seven independent feudal states. The state of Qin eventually grew powerful and efficient enough that it was able to defeat the other six states and complete the unification of China.

Thomas Young double-slit experiment (circa 1800)

which predated the development of quantum mechanics by over a century, demonstrated that light can behave as either a wave or a particle. After passing a beam of light through two narrowly spaced slits, Young observed the characteristic light and dark fringes of interference seen when light acts as a wave. More modern versions that add detectors showing which slit the light passes through, however, show that the light passes through one slit or the other, acting as photons; moreover, the interference pattern disappears. A modern variant, called a quantum eraser, demonstrates quantum entanglement (the ability to exchange information over large distances instantaneously).